Process of making indoxyl and derivatives thereof.



Patented December 15, 1903.

UNITED STATES PATENT OFFICE.

RUDOLF KNIETSOH AND HENRY STALAY ARTHUR HOLT, OF LUDWIGS- HAFEN-ON-THE-Rl-IINE, GERMANY, ASSIGNORS TO THE BADISCHE ANILIN UND SODA FABRIK, OF LUDWIGSHAFEN-ON-THE-RHINE, BAVARIA, GER- MANY, A CORPORATION OF BAVARIA.

PROCESS OF MAKiNG INDOXYL AND DERIVATIVES THEREOF.

SPECIFICATION forming part of Letters Patent No. 746,965, dated December 15, 1903.

Application filed September 9, 1902.

T0 (0Z5 whom it Wtcty concern..-

Be it known that we, RUDOLF Emerson, doctor of philosophy, a subject of the King of Prussia,German Em peror,and HENRY STALAY ARTHUR HOLT, doctor of philosophy, a subject of the King of Great Britain and Ireland, both residing at Ludwigshafen-on-the-Rhine, in the Kingdom of Bavaria, Empire of Germany, have invented new and useful Improvements in Processes of Manufacturing Indoxyl and Derivatives Thereof, of which the following is a specification.

It is known that'on heating phenyl-glycin or its homologues at a high temperature with an alkali hyd roxid or alkali hydroxids either alone or in admixture with an oxid of an alkali earth, such as quicklime, leuco compounds of the indigo series are formednamely, indoxyl or derivatives thereof. By employing quicklime alone without caustic alkaki either no indoxyl compound or but a small quantity thereof is formed, so that quicklime by itself is useless for the manufacture of indigo by the above process on a large scale.

We have discovered that byheatin g phenylglycin or a homologue thereof, including derivatives containing alkyl attached to the nitrogen, with an oxid of an alkaline earth of high molecular weight, such as strontium oxid or barium oxid, indoxyl or its homologues can be obtained in considerably better yield than when phenyl-glycin or a homologue thereof is heated with quicklime. The improvement is apparently greater the higher the molecular weight of the oxid used, since Serial No. 122,702. (No specimensl better results have hitherto been obtained with barium oxid than with strontium oxid.

The following example will serve to illustrare the nature of our in vent-ion, which, how- 0 ever, is not confined to this example. The parts are by weight.

Example: Intimately mix together ten (10) parts of ortho-tolyl-glycin potassium salt and thirty (30)-parts of barium oxid and heat the 5 mixture for about one (1) hour at a temperature of two hundred and ninety to three hundred degrees centigrade, (290 to 300 C.) When cold, introduce the melt into water and work it up to indigo in the known manner.

Instead of barium oxid strontium oxid can be employed. In place of ortho-tolyl-glycin the corresponding quantity of phenyl-glycin potassium salt or other glycin can be employed.

What we claim is 1. The manufacture of indoxyl and derivatives thereof by heating a phenyl-glycin body with a hereinbefore-defined oxid of an alkaline earth.

2. The manufacture of indoxyl and derivatives thereof by heating a phenyl-glycin body with barium oxid.

In testimony whereof we have hereunto set our hands in the presence of two subscribing 65 witnesses.

RUDOLF KNIETSOH. HENRI STALAY ARTHUR HOLT.

Witnesses:

JOHN L. HEINKE, JACOB ADRIAN. 

